Plain English Meaning
The numbers and gauge readings that tell you how the engine is running — things like how fast it's turning, how hot it is, how much oil pressure it has, and how much fuel it's using. You check them against what's normal to confirm the engine is healthy.
Full Definition
The set of measurable operating values that indicate how an aircraft engine is performing, including items such as RPM, manifold pressure, oil pressure, oil temperature, cylinder head temperature, exhaust gas temperature, and fuel flow. Pilots monitor these values against published normal and limit ranges to confirm the engine is operating safely and producing the expected power.
Context Anchor
Seen during engine start, runup, , , , and any time a checks the .